Log Data Source Script (Python)

In this article:
Scripting in Python 3.4 is supported by ULogViewer 3.0+. We recommend reading Scripting in Application (Python) first to learn the basics of scripting.

Samples

The following is sample script to use user-provided pattern (regular expression) to read and filter raw log from file:
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Sub Scripts

There are 3 sub scripts in each log data source script:

Script to Open Raw Log Reader (Required)

The script will be invoked one time when trying to open a reader for reading raw log lines. The type of returned value is LogDataSourceState. Return LogDataSourceState.ReaderOpened if the reader is opened successfully, or return the following values for failure cases:
  • LogDataSourceState.SourceNotFound
    The source of raw log cannot be found.
  • LogDataSourceState.ExternalDependencyNotFound
    One or more external dependencies were not found.
  • LogDataSourceState.UnclassifiedError
    An unclassified error occurred.
Example:
fileName = Context.Options.FileName
if not fileName:
    log_error("No file name specified")
    return LogDataSourceState.UnclassifiedError
 
context.Data["reader"] = StreamReader(fileName, Encoding.UTF8)
return LogDataSourceState.ReaderOpened

Script to Read Raw Log Line (Required)

The script will be invoked every time when trying to read raw log line. The returned value should be a raw log line (string), or Null if there are no more raw log lines to read.
Example:
return context.Data["reader"].ReadLine()

Script to Close Raw Log Reader (Optional)

The script will be invoked one time when closing reader for reading raw log lines. There is no returned value needed.
Example:
reader = context.Data["reader"]
if reader:
    reader.Dispose()
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Context

The following are members of context other than basic members:
  • Options: LogDataSourceOptions
    Data source options for opening reader and reading raw log lines. The following are members of LogDataSourceOptions:
    • Category: string
    • Command: string
    • ConnectionString: string
    • Encoding: System.Text.Encoding
    • EnvironmentVariables: IDictionary<String, String>v4.0+
    • FileName: string
    • FormatJsonData: bool
    • FormatXmlData: bool
    • IncludeStandardError: bool
    • IPEndPoint: System.Net.IPEndPoint
    • IsOptionSet(optionName: string): bool
      Check whether specific option was set with value or not.
    • IsResourceOnAzure: bool
    • Password: string
    • ProcessId: System.Nullable<int>v4.0+
    • ProcessName: stringv4.0+
    • QueryString: string
    • SetupCommands: IList<string>
    • TeardownCommands: IList<string>
    • UserName: string
    • Uri: System.Uri
    • WorkingDirectory: string
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See Also

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